Yaseen Khan, 40, was filling water from a municipality tap in Siddharthanagar, 243 km from here, late Wednesday, a police officer said.
With long queues to fill water, tempers were high as water had not been coming in the Lotan locality at Simarwa square, said the officer.
Yaseen went to fill in water for his household chores and was confronted by some local bullies. He was beaten to death, police said.
The district is facing unprecedented water crisis and serpentine queues are seen at many places.
The body has been sent for post-mortem. An FIR (first information report) has been lodged against three people - Sunil, Meghe and Alok, all residents of a nearby locality Kamarha, said a spokesman of the home department.